1. Field of the Disclosure
This invention relates generally to electrostatographic reproduction machines, and more particularly, to a pneumatic baffle system for cut sheet finishing systems used in such electrostatographic reproduction machines.
2. Description of Related Art
Typically, in an electrostatotographic printing process of printers, such as, U.S. Pat. No. 6,091,929, which is incorporated herein by reference to the extent necessary to practice the present disclosure, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to selectively dissipate the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into contact therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules either to a donor roll or to a latent image on the photoconductive member. The toner attracted to the donor roll is then deposited on latent electrostatic images on a charge retentive surface, which is usually a photoreceptor. The toner powder image is then transferred from the photoconductive member to a copy substrate. The toner particles are heated to permanently affix the powder image to the copy substrate.
In order to fix or fuse the toner material onto a support member permanently by heat, it is necessary to elevate the temperature of the toner material to a point at which constituents of the toner material coalesce and become tacky. This action causes the toner to flow, to some extent, onto fibers or pores of the support members or otherwise upon surfaces thereof. Thereafter, as the toner materials cool, solidification of the toner materials occurs causing the toner material to be bonded firmly to the support member.
A finisher is usually arranged in a post processing position to receive the fused copy substrates or sheets and staple them, if desired. In many such finishing, tamping systems are commonly used to register the sheets in compiler trays. Sheets are usually scuffed against a lead edge registration wall of the compiler trays for various post finisher functions, such as, hole punching, corner stapling, edge stapling, sheet and set stacking, letter or tri-folding, Z-folding, Bi-folding, signature booklet making, set binding, trimming, post process sheet insertion, saddle stitching and others.
In finishers or stackers of this type which stack incoming media sheets directly on top of a previous sheet or stack, it is necessary to ensure the lead edge of each sheet is delivered to a registration wall consistently. A problem is presented due to the interaction of the lead edge of the incoming sheet on the stack surface. As the stack builds the top surface becomes uneven due to curl and ink/toner buildup and can cause the incoming sheet to roll over on the stack surface and jam. Corrugation rolls are often used to put corrugation into the sheet but the effectiveness decreases as the sheets become longer, lighter or if the lead edge of the sheet is deflected by a baffle or guide. The weight of the longer sheets overcome the beam strength of the nip corrugation causing the lead edge of the sheet to droop and inconsistent feed distances result. No static lower baffle is possible because the sheets must drop onto the stack below. Some finisher systems use active shutters to collate the sheets on a flat surface and then move the shutters out to the sides to drop the sheets. This adds a much higher level of complexity and cost. No mechanism or method is known that will keep the sets from migrating away from the registration wall when a scuffer is lifted for engagement of a side tamping function and the sheets consistently migrate away from the registration wall. This impacts the in-set registration which needs to be especially tight for stapled sets.
A decoupling mechanism is shown in U.S. Pat. No. 5,951,006 for passively or actively decoupling an exhaust from a modular air transport systems by diverting an amount of air exiting in a channel in a first module in a direction other than the process direction through use of the Coanda effect. This decouples the amount of air from a downstream module. This is achieved by providing edge surfaces of the channel outlet, formed on top and bottom plates of the first air module, so that one of the two edge surfaces has a larger radius of curvature than the other. An air vent formed by a gap between the other edges and a second module is also provided to assist in the Coanda effect. In U.S. Pat. Nos. 7,140,828 B2 and 6,846,151 B2, objects such as mail are stacked without significant contact therewith by producing laminar air flow over a surface which defines or parallels a desired movement path for the objects. A high speed printed sheet stacking and registration system is shown in U.S. Pat. No. 5,671,920 that employs a vacuum belt sheet transport to hold sheets above a compiled stack while they enter a stacker and uses a normal force system to peel the sheets from the vacuum transport so they can land on top of compiled sheets.
Obviously, there is still a need for an improved compiling and registration finishing apparatus and method that enhances sheet stacking, especially for flimsy sheets.